Abstract
The work described in this thesis concerns the integration of high-efficiency, high-gain and wideband functionality into an S-band Active Electronically Steerable Phased Array Antennas (AESPAA) for microsatellite applications. Several new approaches to the design, with simplicity, of microwave elements (phase shifters, power amplifier and antenna) that constitute the basic building blocks of AESPAA are presented. The influence of aperture coupling and ground plane types on a Reduced Surface Wave (RSW) antenna was explored. Simulation results revealed that the proposed Aperture-Coupled RSW antenna with metamaterial reflector offer a gain improvement of 4.34 dB, with an enhancement in percentage impedance bandwidth of 34% over conventional dual-pin feed RSW antenna. In addition, a study of the effect of metamaterial superstrate cover on the performance of Circularly Polarised Array Antennas (CPAA) has been conducted. Assisted by a numerical simulation tool, a novel Negative Refractive Index (NRI) metamaterial structure has been developed and applied as superstrate for CPAA. Simulation results demonstrate a 3 dB increase in gain with sidelobe enhancement in comparison with conventional CPAA. Furthermore, this thesis also presents the development of a robust, power efficient, compact and high-power S-band phase shifters based on packaged microelectromechanical systems (MEMS), which is compatible with microsatellite power bus and offers the high reliability of cold switching. Finally, this thesis has developed design techniques to implement an S-band Gallium Nitride (GaN)-based power amplifier for application in AESPAA, allowing for low-cost, compact, power efficient, and high data rate power amplifier for microsatellites. Under continuous wave (CW) operation, performance measurements for the proposed power amplifier demonstrated 29.5-39.5 dBm (0.9-9 W) of output power and 26-55% associated power added efficiency over a 2.133-2.333 GHz matched frequency band.